G550 CROSSES RWY 25R AT LAX WITHOUT CLRNC.

Narrative

ACFT AND CREW ARRIVED AT LAX ABOUT XA00 FOLLOWING A FLT FROM ZZZZ. AFTER A DELAY OF NEARLY 2 HRS; FOR IMMIGRATION CTL OF A CREW MEMBER; ACFT DEPARTED GA RAMP. RWY 25L WAS CLOSED FOR EXTENSIVE CONSTRUCTION. ESTABLISHED ON TXWY G; P2 RECEIVED WHAT UNDERSTOOD TO BE A CLRNC TO 'CROSS RWY 25L AND R; HOLD SHORT OF RWY 25R AND CONTACT TWR 120.95.' P1 ACKNOWLEDGED THE SAME UNDERSTOOD CLRNC; P2 LOOKED TOWARDS THE THRESHOLD OF RWY 25R AND SAW NO ACFT. CREW UNDERSTANDING OF THE CLRNC WAS TO CROSS BOTH RWYS AND HOLD ON THE FAR SIDE OF THE RWY SHORT OF THE THRESHOLD (ON TXWY B OR C); WHILE CONTACTING TWR -- A TYPICAL CLRNC IN THE NOT TOO DISTANT PAST IN THE US. IN FACT; THERE WAS AN ACFT AT THE THRESHOLD BUT ITS COLOR DID NOT CONTRAST SUFFICIENTLY TO REGISTER VISUALLY. P1 DOES RECALL ANNOUNCING THAT THE L SIDE WAS CLR AND DOES RECALL PHYSICALLY CHKING. P1 THEN PROCEEDED TO CROSS RWY 25R AFTER P2 STATED CLRED TO CROSS. BY THEN WE WERE ENTERING THE RWY (AS BELIEVED TO BE CLRED) AND P1 OBSERVED AN RJ BRAKING TO A STOP ABOUT 2000 FT AWAY. THE INTXN OF TXWY G IS ABOUT 3000-4000 FT FROM THE THRESHOLD. CREW THEN HEARD TWR SAY TO THE RJ THAT THEY 'HAD NO CONTACT WITH THE GULFSTREAM.' NO DAMAGE; OTHER THAN TO NERVES AND PROFESSIONAL PRIDE RESULTED. AFTER REACHING THE DEST; CREW CALLED LAX TWR WHO VERIFIED THAT THEIR CLRNC WAS ONLY TO 'CROSS RWY 25L (THE CLOSED RWY) AND HOLD SHORT OF RWY 25R AND CONTACT TWR.' P1 ASKED GULFSTREAM LGB TO DOWNLOAD THE CVR IN ORDER TO BETTER UNDERSTAND THE BREAKDOWN OF COMS. THERE WAS UNDOUBTEDLY A FAILURE ON THE CREW'S PART TO UNDERSTAND AND COMPLY WITH A CLRNC AS EVIDENCED BY THE TWR'S REVIEW OF ATC TAPES. A REVIEW OF ACFT TAPES MAY SHED LIGHT ON THE CREW'S FAILURE ALTHOUGH IT MAY ASCRIBE TO SEVERAL FACTORS IN THE FOOTNOTE BELOW. SUBJECTIVE COMMENTS. AS A SAFETY ORIENTED PLT; I AM KEENLY INTERESTED IN PROCESS UNDERSTANDING AND GROWTH (AT ATC AND USER LEVELS). WITH THAT IN MIND; THE FOLLOWING MAY BE NOTEWORTHY: FATIGUE AT THE END OF A LONG DUTY DAY. (EVENT OCCURRED AT ABOUT 15 HRS; INCLUDING PREFLT AND 3 HRS BUNK REST FOR EACH PLT ENRTE FROM ZZZZ. 16 HRS IS ACCEPTABLE TO OUR SOP'S WITH AN AUGMENTED CREW OF 3 PLTS.) TWR'S FAILURE TO ISSUE A MORE CONCISE CLRNC SUCH AS; 'CLRED TO CROSS RWY 25L; HOLD SHORT OF RWY 25R ON TXWY G/PRIOR TO XING OR CONTACT TWR TO CROSS.' NON-STANDARD ICAO CAUTION LIGHTS ARE FLASHING IMBEDDED YELLOW (NOT A 'RED BAR'). I DO NOT RECOLLECT IF THEY ARE INTENDED TO BE SWITCHED OFF PRIOR TO XING. LIKE MANY BUSY ARPTS; LAX USES CONTRACTED CLRNCS AND DEPARTS FROM STANDARD PHRASEOLOGY (BOTH FAA AND ICAO) THAT MAY HAVE CONTRIBUTED TO THIS INCIDENT AND COULD EASILY DO SO IN THE FUTURE.